君の参照は。〜classとfunctionと循環参照の話〜

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takasek؂ಜ ࠷৽࡞ ɹ܅ ͷ ࢀ র ͸ ɻ 2016/9/16 Վ෣ب࠲.tech #11 1

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·ͩdeinitͨ͜͠ͱͷͳ͍܅ (class) Λɺ ڧࢀর͍ͯ͠Δɻ 2

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ɹ࿩͕௕͍ͷͰɺ ɹ·ͣ͸݁࿦ɻ 5

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classͷ Πϯελϯεϝιου͸ self΁ͷڧࢀরΛ ͍࣋ͬͯΔͷͰ ؾΛ͚ͭΖɻ 6

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Ͱ͸ ຊ୊ελʔτ! 7

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ϘλϯΛͻͱ͚ͭͩ࣋ͭ UIViewαϒΫϥεͷίϯϙʔωϯτΛ࡞ͬͨͱ͠·͢ɻ ﬁnal class MyComponent: UIView { @IBOutlet private var button: UIButton! //Button͕ԡ͞ΕͨΒɺcallbackΛ࣮ߦ var callback: (() -> Void)? @IBAction func didButtonPush() { callback?() } } 8

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͜ͷίϯϙʔωϯτʹcallbackͱͯؔ͠਺Λ౉ͯ͠ɺ ViewControllerͰॲཧͰ͖ΔΑ͏ʹ͠·͢ɻ ﬁnal class ViewController: UIViewController { @IBOutlet private var component: MyComponent! override func viewDidLoad() { super.viewDidLoad() component.callback = { ͳΜ͔ॲཧΛ͢Δ() } } deinit { print("deinit") } } 9

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ﬁnal class ViewController: UIViewController { @IBOutlet private var component: MyComponent! override func viewDidLoad() { super.viewDidLoad() component.callback = { ͳΜ͔௕͍ॲཧ() if something.isͳΜͨΒ { ଞͷ௕͍ॲཧ() } else { something.΄͛΄͛() } } } deinit { print("deinit") } } ! callbackͷத਎͕๲ΒΜͰ͖ͨ 10

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ﬁnal class ViewController: UIViewController { @IBOutlet private var component: MyComponent! override func viewDidLoad() { super.viewDidLoad() component.callback = { self.doHogehoge() } } private func doHogehoge() { ... } deinit { print("deinit") } } ☺ ϝιουʹ੾Γग़ͯ͠ɺ͖ͬ͢Γ 11

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!…଴ͯΑʁ component.callback = { self.doHogehoge() } !Ϋϩʔδϟͷதʹself͕ొ৔͢Δ৔߹͸ɺ॥؀ ࢀরʹؾΛ͚ͭΔඞཁ͕͋ΔΜͩͬͨͳ…ʁ 12

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!॥؀ࢀর self ➡ self.component self.component ➡ self.component.callback self.component.callback ➡ self ɹ let closure = { //Ϋϩʔδϟ͕selfΛڧࢀরͰΩϟϓνϟ͍ͯ͠Δ self.ʙʙʙ } 13

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! ͳΒ͜ΕͰ… component.callback = { [weak self] in self?.doHogehoge() } ! ऑࢀরʹͯ͠ɺ᠘Λ՚ྷʹճආʂ 14

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ﬁnal class ViewController: UIViewController { @IBOutlet private var component: MyComponent! override func viewDidLoad() { super.viewDidLoad() component.callback = { [weak self] in self?.doHogehoge() } } private func doHogehoge() { // ... } deinit { print("deinit") } } ɹ ☺ ͖ͬ͢ΓΞήΠϯ 15

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... { ... component.callback = { [weak self] in self?.doHogehoge() } } private func doHogehoge() { // ... } ! ͍΍ɺͰ΋଴ͯΑ… ɹ ͜ͷΫϩʔδϟɺແବ͡Όͳ͍͔ʁ 16

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! ͦ͏ͩɺSwiftͰ͸ ɹ ؔ਺΋ୈҰڃΦϒδΣΫτͩ ﬁnal class MyComponent: UIView { var callback: (() -> Void)? } ﬁnal class ViewController: UIViewController { private func doHogehoge() { } ! ͦͯ͠ϝιου doHogehoge ΋ ɹ ϓϩύςΟ callback ͱಉ͡ ()->Void ܕ ɹ ͱ͍͏͜ͱ͸… 17

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ɹ ɹ component.callback = doHogehoge ɹ ! …͜Εͩʂ 18

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ﬁnal class ViewController: UIViewController { @IBOutlet private var component: MyComponent! override func viewDidLoad() { super.viewDidLoad() component.callback = doHogehoge // ! } private func doHogehoge() { // ... } deinit { print("deinit") } } ! ܕ͸߹ͬͯΔʂ ɹ ͜ͷॻ͖ํ…coool͡Όͳ͍!? ɹ doHogehogeͷதͰ͸self࢖ͬͯͳ͍͠ʂ 19

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ͱࢥͬͨΒɺҧͬͨ 20

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deinit { print("deinit") } ! deinitɺݺ͹Εͯͳ͍ΜͰ͚͢Ͳʂʂ 21

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!॥؀ࢀরͷग़དྷ্͕Γ self ➡ self.component self.component ➡ self.doHogehogeϝιου self.doHogehogeϝιου ➡ self ɹɹɹɹɹɹɹɹɹɹɹɹɹ "!? 22

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ϝιου͸҉໧తʹ self΁ͷڧࢀরΛ ͍࣋ͬͯΔ 23

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ϝιου͕functionܕ ͔ͩΒͱݴͬͯɺ ܰ཰ʹଞͷܕʹ౉ͯ͠ ॴ༗ͤͯ͞͸͍͚ͳ͍ 24

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͜͜Ͱ ಥવͷΫΠζʂ 25

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͜Ε͔Βɺ͍Ζ͍ΖͳfunctionܕΛɺ͍Ζ͍ΖͳܗͰ component.callback ϓϩύςΟʹ౉͠·͢ɻ ָ͠Έํ ·ͣɺίʔυΛఏࣔ͠·͢ɻ ఏࣔ͞Εͨίʔυ͕॥؀ࢀরΛى͔͜͢ɺͬ͘͡Γߟ͑ ͯΈ·͠ΐ͏ɻ ϖʔδΛΊ͘Ε͹౴͑߹Θͤɻ ݁Ռʢ ݈શ! or ॥؀ࢀর" ʣ͕෼͔Γ·͢ɻ ΫΠζؾ෼Ͱ௅ઓͯ͠Έ͍ͯͩ͘͞Ͷɻ 26

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ݕূ༻ϓϩδΣΫτ https://github.com/ takasek/ RecursiveReferenceSample projectΛϏϧυͯ͠ɺࣗ෼Ͱ ಈ͔ͯ͠Έͯ΋ָ͍͔͠΋͠ Ε·ͤΜɻ 27

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here we go! 28

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ϝιου ﬁnal class ViewController: UIViewController { private func doHogeMethod() { print("method") } func conﬁgureButtonAction() { component.callback = doHogeMethod } } ݁Ռ͸… 29

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ϝιου ﬁnal class ViewController: UIViewController { private func doHogeMethod() { print("method") } func conﬁgureButtonAction() { component.callback = doHogeMethod } } ݁Ռ: ॥؀ࢀর! 30

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ϝιου([unowned self]ͳΫϩʔδϟ͔ΒݺͿ) ﬁnal class ViewController: UIViewController { private func doHogeMethod() { print("method") } func conﬁgureButtonAction() { component.callback = { [unowned self] in self.doHogeMethod() } } } ݁Ռ͸… 31

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functionܕϓϩύςΟ ﬁnal class ViewController: UIViewController { let functionTypeProperty = { print("function-type property") } func conﬁgureButtonAction() { component.callback = functionTypeProperty } } ݁Ռ͸… 33

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functionܕϓϩύςΟ(தͰselfΛ࢖͏) ﬁnal class ViewController: UIViewController { let functionTypePropertyUsingSelf = { print("function-type property using self", self) } func conﬁgureButtonAction() { component.callback = functionTypePropertyUsingSelf } } ݁Ռ͸… 35

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let functionTypePropertyUsingSelf = { print("function-type property using self", self) } func conﬁgureButtonAction() { component.callback = functionTypePropertyUsingSelf } ɹ !଴ͬͯ଴ͬͯɺ͜ΕϚδͰ॥؀ࢀরى͖ͳ͍ͷ!? ͬͯͳΓ·͢ΑͶɻ ϚδͰ͢ɻ 37

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ؾΛऔΓ௚ͯ͠ɻ ͜͜·Ͱ͸classΠϯελϯεͷϝϯόฤͰ͕ͨ͠ɺ ͔͜͜Β͸ϩʔΧϧείʔϓฤͰ͢ɻ func conﬁgureButtonAction() ͷதͰؔ਺Λ࡞Δύλʔϯɻ 38

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ϩʔΧϧfunction ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { func localFunc() { print("local func") } component.callback = localFunc } } ݁Ռ͸… 39

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ϩʔΧϧfunction ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { func localFunc() { print("local func") } component.callback = localFunc } } ݁Ռ: ݈શ! 40

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ϩʔΧϧfunction(தͰselfΛ࢖͏) ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { func localFuncUsingSelf() { print("local func using self", self) } component.callback = localFuncUsingSelf } } ݁Ռ͸… 41

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ϩʔΧϧΫϩʔδϟ ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { let localClosure = { print("local closure") } component.callback = localClosure } } ݁Ռ͸… 43

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ϩʔΧϧΫϩʔδϟ ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { let localClosure = { print("local closure") } component.callback = localClosure } } ݁Ռ: ݈શ! 44

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ϩʔΧϧΫϩʔδϟ(தͰselfΛ࢖͏) ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { let localClosureUsingSelf = { print("local closure using self", self) } component.callback = localClosureUsingSelf } } ݁Ռ͸… 45

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ϩʔΧϧΫϩʔδϟ(தͰunowned selfΛ࢖͏) ﬁnal class ViewController: UIViewController { func conﬁgureButtonAction() { let localClosureUsingUnownedSelf = { [unowned self] in print("local closure using unowned self", self) } component.callback = localClosureUsingUnownedSelf } } ݁Ռ͸… 47

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͜͜·Ͱͷ·ͱΊ » ݈શ!ͳύλʔϯ » ϝιου([unowned self]ͳΫϩʔδϟ͔ΒݺͿ) » functionܕϓϩύςΟ » functionܕϓϩύςΟ(தͰselfΛ࢖͏) » ϩʔΧϧfunction » ϩʔΧϧΫϩʔδϟ » ϩʔΧϧΫϩʔδϟ(தͰunowned selfΛ࢖͏) » ॥؀ࢀর"͕ى͜Δύλʔϯ » ϝιουΛ௚઀౉͢ » ϩʔΧϧfunction(தͰselfΛ࢖͏) » ϩʔΧϧΫϩʔδϟ(தͰselfΛ࢖͏) 49

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͞Βʹ·ͱΊ » Ϋϩʔδϟ͸ɺதͰ࢖ΘΕΔreference typeΛڧࢀরΩϟϓν ϟ͢Δ » unowned, weakΛ࢖͑͹ڧࢀরΩϟϓνϟ͸ආ͚ΒΕΔ » classΠϯελϯε͕࣋ͭϝιου͸ɺself΁ͷࢀরΛ࣋ͭ » classΠϯελϯε͕࣋ͭfunctionܕϓϩύςΟ͸ɺselfΛڧࢀ র͠ͳ͍ » தͰselfΛ࢖͏functionܕϓϩύςΟͰ͢ΒɺselfΛڧࢀর ͠ͳ͍ » Կނ…!? 50

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> தͰselfΛ࢖͏functionܕϓϩύςΟͰ͢ΒɺselfΛڧ ࢀর͠ͳ͍ …ຊ౰ʹʁ 51

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let functionTypePropertyUsingSelf = { print("function-type property using self", self) } self…? 52

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print("function-type property using self", self) ͷ݁Ռ (Function) …ͩͱ…!? 54

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functionܕϓϩύςΟ(தͰselfΛ࢖͏) …Λ΋͏Ұ౓Α͘Α͘ݟͯΈΔͱɺ ﬁnal class ViewController: UIViewController { let functionTypePropertyUsingSelf = { print("function-type property using self", self) } } ! ͜ͷfunction͕࡞ΒΕΔ࣌ʹɺ ɹ self( ViewController )ͬͯ·ͩଘࡏͯ͠ͳ͘ͳ͍ʁ ɹ ଘࡏ͠ͳ͍΋ͷ͸ɺࢀর΋Ͱ͖ͳ͍ΑͶʁ 55

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ͪͳΈʹɺ ͜ͷselfΛऑࢀরΩϟϓνϟ͠Α͏ͱ͢Δͱ… ﬁnal class ViewController: UIViewController { let functionTypePropertyUsingSelf = { [weak self] in print("function-type property using self", self) } } ऑࢀরʹͰ͖Δͷ͸ɺ classܕɺ͋Δ͍͸classܕઐ༻ͷϓϩτίϧ͚ͩɻ self͸ ViewController ܕͷΠϯελϯεͰ͸ͳ͍ͷͰɺ ऑࢀরΩϟϓνϟ΋ෆՄೳͬͯ͜ͱͰ͢Ͷɻ 56

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The Swift Programming Language (Swift 3): Closures ΑΓ Closure expressions are unnamed closures written in a lightweight syntax that can capture values from their surrounding context. surrounding contextͬͯͷ͸ɺͦ͏͍͏͜ͱ ʢͩͱࢥ͏ʣɻ 57

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͞ΒʹͪͳΈʹɺ pure swiftͳclass (=NSObjectͷαϒΫϥεͰ͸ͳ͍) ͩͱ…… self͸ଘࡏࣗମɺͯ͠ͳ͍ʂ 58

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·ͱΊʢ׬શ൛ʣ » Ϋϩʔδϟ͸ɺதͰ࢖ΘΕΔreference typeΛڧࢀ রΩϟϓνϟ͢Δ » unowned, weakΛ࢖͑͹ڧࢀরΩϟϓνϟ͸ආ ͚ΒΕΔ » classΠϯελϯε͕࣋ͭϝιου͸ɺself(classΠ ϯελϯε)΁ͷڧࢀরΛ࣋ͭɻ͠Όʔͳ͍ɻ » classΠϯελϯεͷfunctionܕϓϩύςΟͰ͸ɺͦ ΋ͦ΋self ≠ ॴ༗͍ͯ͠ΔclassΠϯελϯεࣗ਎ 59